1. Field of the Invention
This invention relates to web handling systems and methods and more particularly to web inspection and removal of unwanted web sections.
2. Background Information
In continuous web printing and handling operations, a web that is typically composed of paper, is driven on a large roll through a succession of web utilization devices. In general, these devices include one or more printers, and associated cutters, stackers, bindersxe2x80x94and a large variety of other web utilization/enhancement devices. It is common for long runs of web wound on a roll to include several splices within the overall stream. A splice is where two discrete ends of continuous web are joined together, typically in an overlapping relation using adhesive, tape or another joining mechanism. It is generally undesirable to process printing or other operations on a splice section. The resulting cut sheet exhibits generally inferior and unacceptable quality.
One commonly employed technique for dealing with splices is to visually scan the web as it passed through a given point in the process stream, and attempt to identify/flag a found splice section. If possible, the flagged splice is manually removed from the web, or from the resulting stream of sheets. Alternatively, the printing is adjusted to avoid the splice section. If the splice is not detected sufficiently early (before any printing or post-production operations have occurred on the web), and then it may become incorporated into a page in the overall print job. As such, it would be necessary to reprint and re-sort the splice-containing page, or to discard the entire job section containing the splice page. Each of these outcomes expends valuable production time and/or resources.
Commonly assigned U.S. Pat. No. 5,628,574, entitled WEB ERROR RECOVERY DIVERT SYSTEM by H. W. Crowley teaches a technique for diverting sheets containing errors therein from an overall web processing job. The teachings of this patent are expressly incorporated herein by reference. It should be possible, based upon the ability to divert errors, to remove unwanted splice sections from a web.
Accordingly, it is an object of this invention to provide a system and method for detecting and removing web sections having splices without affecting the overall flow and makeup of a web processing job.
This invention overcomes the disadvantages of the prior art by providing a system and method for detecting and removing splice sections from a continuous web in a web processing job that detects a splice, identifies/flags a selected length containing the splice, stores or otherwise records the splice position in the web stream, tracks the length to an appropriate divert location and, whence removes the affected section (or otherwise marks it as erroneous/undesired).
In a preferred embodiment, a detector is positioned adjacent a feed location for the continuous web, upstream of a printer or other web processing device. A tracking mechanism such as a mark detector determines the associated location of a splice and maintains, using a controller having a shift register, counter or other tracking device, information on the relative position of the splice section in the stream. If the downstream device is a printer, another tracking mechanism within the printer determines when the splice section is presented to the print engine, and omits printing from this identified splice section. If the downstream device is a cutter, then the cutter, using a web movement tracking mechanism, determines when the splice section is presented, and cuts the splice section for subsequent removal from the stream. In particular, where printing is omitted from a section, and a further downstream cutter is provided, the cutter, using the movement tracking mechanism, cuts the non-printed spliced section for subsequent removal. Removal of the splice-containing section can involve a divert gate that opens when the cut splice section is adjacent thereto and then again closes to enable further sheets to pass there along. In general, the remaining sheets in the stream are unaffected by the diverted splicer sheet as it is removed before final binding or other grouping of sheets occurs, and the order of sheets, with the splice-containing sheet removed is unchanged.